Learn Raspberry Pi Scratch 2 Tutorial with Science Buddies Kit

Table of Contents

1. Introduction
2. Setting Up Scratch 2 on Raspberry Pi
3. Writing Your First Simple Program
4. Adding Commands to Steer the Cat
5. Using Variables to Control Cat's Movement
6. Making the Cat Display Text and Play Sounds
7. Making the Cat Move Automatically
8. Adding Multiple Sprites to Your Program
9. Changing the Background of the Stage
10. Controlling Raspberry Pi's GPIO Pins with Scratch

Introduction

In this article, we will explore how to use Scratch 2 on your Raspberry Pi. Scratch is a graphical programming environment that allows beginners to write computer programs by clicking and dragging colored blocks of code. It provides a visual and interactive way to learn coding without the need for writing lines of text. We will cover the setup process, writing your first simple program, adding commands to steer the cat sprite, using variables to control cat's movement, making the cat display text and play sounds, making the cat move automatically, adding multiple sprites to your program, changing the background of the stage, and controlling Raspberry Pi's GPIO pins with Scratch.

Setting Up Scratch 2 on Raspberry Pi

To use Scratch 2 on your Raspberry Pi, you can either use the SD card that came with the Science Buddies Raspberry Pi kit or install Scratch 2 separately if you have your own SD card. If you are using the kit's SD card, there should be a shortcut to Scratch 2 on the desktop. Double-click that shortcut to open Scratch 2. If you are using your own SD card, click on the Raspberry Pi logo in the upper left corner of the screen, go to programming, and then select Scratch 2. Make sure you select Scratch 2 and not other versions of Scratch that are available for Raspberry Pi.

Writing Your First Simple Program

Let's dive right into writing your first simple program in Scratch. First, click on the "Events" button towards the top of your screen. Then, click and drag the block that says "when space key pressed" to the blank area on the right part of your screen. Next, click on the "Motion" button, drag the block that says "move 10 steps," and place it next to the previous block. The blocks in Scratch have bumps on their edges to Show where you can snap them together. Snap the "move 10 steps" block below the "when space key pressed" block. Now, you have written your first very simple program. When you press the space key on your keyboard, the cat sprite on the stage will move 10 steps forward. You can double-click on the number 10 to change the distance the cat moves in one step.

Adding Commands to Steer the Cat

To add commands that allow You to steer the cat sprite in different directions, click on the "Events" button again. Drag out the "when one space key pressed" block and change the key to the left arrow. Then, click on the "Motion" button, drag out the "turn counterclockwise 15 degrees" block, and snap it below the previous block. Now, when you press the left arrow key, the cat sprite will rotate counterclockwise. Similarly, you can add blocks for the up arrow to move the cat forward. It would be nice to have the ability to steer the cat in both directions, so let's add one more set of blocks. This time, add the blocks for turning the cat clockwise.

Using Variables to Control Cat's Movement

Using variables can make it easier to control the cat sprite's movement. Click on the "Data" button and Create a variable called "angle." This variable will store the value of how far the cat should turn each time you press the arrow keys. Use the "set angle to" block to set the angle to a specific value, such as 15 degrees. Then, drag the "angle" variable into each text box that requires an angle value. Now, you only need to update the angle value in one location, and it will Apply to all the Relevant blocks.

Making the Cat Display Text and Play Sounds

Scratch allows you to make the cat sprite display text or play sounds when it moves. Click on the "Looks" button, drag out the "say hello for 2 seconds" block, and place it below the "move 10 steps" block. Now, every time the cat moves forward, it will say "hello" for 2 seconds. To make the cat play a sound, click on the "Sound" button, drag out the "play sound" block, and place it below the "say hello for 2 seconds" block. The cat will now make a "meow" sound every time you press the up arrow key.

Making the Cat Move Automatically

If you want the cat to move automatically without pressing any keys, you can use a loop in Scratch. Click on the "Control" button and drag out the "forever" block. This block will repeat the code inside it continuously. You can use the "move" and "turn" blocks inside the forever loop to make the cat repeat its motion. Make sure to use variables for the distance and angle values instead of hard-coded numbers. For example, you can use the "move distance steps" and "turn angle degrees" blocks. You can adjust the values of the variables and see the cat's movement. To make the motion visible, you can add a wait block in between the movement commands to create a delay.

Adding Multiple Sprites to Your Program

In Scratch, you can add multiple sprites to your program. To add a new sprite, click on the "Sprites" area in the lower left corner of the Scratch window. You can import additional sprites from the existing Scratch library, draw your own, upload an image, or take a picture with a webcam. Once you have added multiple sprites, each sprite will have its own script. Make sure to select the sprite you want to work with by clicking on it in the "Sprites" area.

Changing the Background of the Stage

You can also change the background of the stage in Scratch. By default, the background is white, but you can import an image, draw your own, upload an image, or take a picture to use as the background. Changing the background can help enhance the visual appearance of your program.

Controlling Raspberry Pi's GPIO Pins with Scratch

For Science Buddies projects, you may need to control the Raspberry Pi's GPIO pins using Scratch. To access the GPIO pins, you need to add an extension to Scratch. Click on the "More Blocks" button, then select "Add an Extension." Choose the "Pi GPIO" extension and click OK. Once added, you will have two new blocks available to set and Read values on the GPIO pins.

Highlights

• Scratch 2 is a graphical programming environment that allows beginners to learn coding by clicking and dragging colored blocks of code.
• You can set up Scratch 2 on Raspberry Pi using the provided SD card or by installing it separately.
• Writing your first program involves using event blocks and motion blocks to make the cat sprite move.
• By adding commands, you can steer the cat sprite in different directions using arrow keys.
• Using variables, you can control the distance and angle of the cat's movements.
• Scratch allows the cat sprite to display text and play sounds using the "Looks" and "Sound" blocks.
• You can make the cat move automatically using loops and adjusting the values of variables.
• Adding multiple sprites and changing the background can enhance the visual appeal of your Scratch program.
• With the Pi GPIO extension, you can control the Raspberry Pi's GPIO pins using Scratch.

FAQ

Q: Can I use Scratch 2 on other devices besides Raspberry Pi? A: Yes, Scratch 2 is available for various platforms like Windows, macOS, and Linux, in addition to Raspberry Pi.

Q: Are there any other programming environments similar to Scratch? A: Yes, there are other graphical programming environments like Scratch, such as Blockly, Snap!, and Code.org's App Lab.

Q: Can I create my own sprites and backgrounds in Scratch? A: Yes, Scratch provides tools for creating and editing sprites and backgrounds. You can draw your own, import images, or use existing assets from the Scratch library.

Q: How can I share my Scratch projects with others? A: Scratch allows you to share your projects online by uploading them to the Scratch website. Others can then view and interact with your projects.

Q: Can Scratch be used for more advanced programming tasks? A: While Scratch is primarily designed for beginners, it is possible to create more complex programs using advanced programming concepts like variables, loops, and conditionals.

Q: Is it possible to use Scratch to control hardware other than Raspberry Pi's GPIO pins? A: Yes, Scratch has extensions for controlling various hardware devices through additional interfaces like Arduino and LEGO Mindstorms.

Q: Can I program games in Scratch? A: Yes, Scratch is a popular choice for creating games due to its intuitive and visual nature. Many game development tutorials and resources are available for Scratch.

Q: Are there any limitations to what I can do in Scratch? A: While Scratch is a powerful tool for learning programming, it does have some limitations compared to traditional text-based programming languages in terms of performance and advanced features.

Q: Can I use Scratch for professional software development? A: While Scratch is more suitable for educational purposes and simple projects, it can be a stepping stone towards learning more advanced programming languages and concepts used in professional software development.

Q: Where can I find more resources and tutorials for Scratch? A: The Scratch website offers a wide range of resources, tutorials, and examples to help you get started and expand your Scratch programming skills.